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Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Published on: April 8, 2020

Synergy between pair coupled cluster doubles and pair density functional theory.

Alejandro J Garza¹, Ireneusz W Bulik¹, Thomas M Henderson²

¹Department of Chemistry, Rice University, Houston, Texas 77251-1892, USA.

The Journal of Chemical Physics

|February 2, 2015

Summary

Pair coupled cluster doubles (pCCD) methods now include dynamic correlation by blending with density functionals. This approach enhances accuracy for complex chemical problems with minimal computational cost.

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Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

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Published on: May 27, 2020

Area of Science:

Quantum chemistry
Computational physics

Background:

Pair coupled cluster doubles (pCCD) accounts for static correlation at low cost.
Static and dynamic electron correlation are crucial for accurate chemical predictions.
Existing methods struggle to balance accuracy and computational expense for these correlations.

Purpose of the Study:

To develop and evaluate new computational methods combining pCCD with density functional theory (DFT).
To incorporate dynamic correlation into pCCD without introducing double counting.
To improve the description of chemical systems requiring both static and dynamic correlation.

Main Methods:

Combining pair coupled cluster doubles (pCCD) with Kohn-Sham functionals.
Utilizing on-top pair density functionals to capture dynamic correlation.
Developing pCCD+DFT blends with minimal computational overhead.

Main Results:

The pCCD+DFT blends significantly improve upon pCCD for systems with both static and dynamic correlation.
The computational cost increase for the pCCD+DFT blends is negligible.
The enhanced methods provide a more accurate description of challenging chemical problems.

Conclusions:

pCCD is well-suited for integration with pair density functionals due to its favorable properties.
pCCD+DFT blends offer a promising, computationally efficient approach for multireference problems.
This fusion method enhances the capabilities of pCCD for describing complex electronic structures.